Mount structure for electric lamps



Jan. 20, 1948.

W. H. WILLIS MOUNT STRUCTURE FOR ELECTRIC LAMPS Filed Feb. 28, 1947InvenTor:

WirfiField H. Wi-llis,

His ATTor-ney- Patented Jam, 1948 MOUNT STRUCTURE FOR ELECTRIC LAMPSWinfield H. Willis, Bedford, Ohio,

General Electric Company,

New York assignor to a corporation of Application February 28, 1947,Serial No. 732L584 Claims. (Cl. 176'29) My invention relates to electricincandescent lamps and similar devices, and more particularly to asupport arrangement for the mounts of such lamps. The invention is ofparticular utility in connection with electric incandescent lamps of thedouble-ended tubular type having a base at each end and a filamentextending longitudinally of the lamp, such as shown and described in U.S. Patents 2,032,791, P. O. Cartun, and 2,158.849, H. D. Blake, assignedto the assignee of the present invention. 1

Lamps of the above mentioned double-ended tubular type are in generaluse at present, such lamps being commonly known as Lumiline lamps. Asmanufactured at present, these lamps comprise a tubular glass envelopehaving metal end caps or bases sealed to the opposite ends thereof andan elongated mount supported within the envelope between the metal endcaps. The mount comprises an elongated filament extending longitudinallyof the envelope and supported by an elongated stay member which isresiliently compressible longitudinally between the end caps and whichis provided at its opposite ends with terminal wires or end conductorswhich are electrically connected to the ends of the filament. The saidterminal conductors of the stay member are formed with loop portionswhich bear against the end caps and encircle inward bosses on the saidcaps.

With lamps of the above described construction, the mounts are free torotate or turn within the envelope about the longitudinal axis thereof,the only restraint to such rotation being the frictional resistancewhich is exerted on the terminal conductor loops by the end cap, byreason of the pressure engagement therebetween. As a result, the mountsof such lamps, particularly in those applications where the lamps aresubject to frequent shocks and vibration, actually do undergo a certainamount of rotation within the envelope. Obviously, the prevention ofsuch mount rotation is to be desired, especially in those cases wherethe envelope is provided with a light-reflecting coating around aportion of its circular extent. In such cases it is preferable tomaintain the mount in fixed relation to the reflector, with the staymember located within the reflector, in order to prevent the stay memberfrom casting a shadow or producing a dark spot in the projected beam oflight.

It is an object of myinvention, therefore, to provide an electric lampof the character described having amount which will not be subject torotation within the lamp envelope.

Another object of my invention is to provide an electric incandescentlamp of the character described having means for positively locking thelamp mount against rotation within the lamp envelope. 4

Still another object of my invention is to provide an electricincandescent lamp of the character described having a reflective coatingon a portion of the envelope wall and a mount structure locked inpredetermined relation to the said reflector.

Further objects and advantages of my invention will appear from thefollowing detailed description of a species thereof and from theaccompanying drawing in which: n

Fig. 1 is a fragmentary elevation, partly in section, of an electricincandescent lamp comprising my invention; Fig. 2 is an enlargedperspective view, partly broken away, of one end of the lamp shown inFig, 1; Fig. 3 is a transverse section taken on the line 3-3 of Fig. 1;and Fig. 4 is a longitudinal section, on the line 4-4 of Fig. 3, of theend of the lamp shown in Fig. 2.

Referring to the drawing, the lamp there shown is of the double-endedtubular type shownin the above mentioned U. S. Patents 2,032,791 and2,158,849, and comprises an elongated sealed envelope I consisting of atubular glass bulb 2 having disc-shaped metal end caps or bases 3, 4fusion-sealed to its opposite ends to form end walls for the envelopeand contact terminals for the lamp. The said end caps or discs 3, 4 arepreferably made of a metal or alloy which has a coeflicient of expansionapproximately the same as that of the glass of which the tube 2 is madeand which seals readily thereto by fusion. For a soft glass tube 2, theend caps 3, 4 are preferably made of an iron alloy containing about 25to 30 per cent chromium. The end caps 3, 4 are preferably concave ordish-shaped so that they may be made of thin material while retainingadequate strength, and they are provided with centrally located bosses5, 6 which project axially inward of the envelope l. The particular lampillustrated is provided with a reflector which may be in the form of areflecting coating 1 on the glass tube 2 extending substantially thefull length thereof and around a portion (approximately one-half in theparticular case shown) of the circular extent of the glass tube. Thereflecting coating 1 may be of aluminum, silver, or other suitablereflecting material. Instead of the reflector I, the glass tube 2 may beprovided with other light-modifying means extending around a portion ofits circular extent, such as by frosting practically straight.

the glass or providing an enamel coatingthereon.

The envelopel is exhausted through an aperture (not shown) at the centeroi; the end cap l, the

cavity formed by the'boss 6.

Mounted within and extending longitudinally ass e779 In accordance withthe invention, interlocking means 2| are provided on the. mount a andthe endcap 3 for preventing rotation or turning of the mount within theenvelope I about the axis of the envelope. l is an elongated lamp mount8 comprising a composite stay member 9 and an elongated filament itsupported thereby. The

filament supporting structure or stay member 9..

comprises an elongated straight center section it:

extending longitudinally of the tube 2 adjacent the wall thereof andprovided at its opposite ends with terminal wire or end conductorextensions l2, it. The center section ll of the stay'member 9 ispreferably in the form of channel-shaped member of a suitable material,for.'instance a stainless steel such as that commercially known asAllegheny metal. Y electrically connected, as by welding, t one end ofthe channel member ll while the other ter- The terminal wire it is ofthe latter. For thispurpose, the top wall 22 of the boss 5 (which wallis of convex or dishshape) is provided with a notch or groove 23extending transversely of the envelope, and the ad- I jacent terminalwire i2 is bent to provide a laterally extending ofiset anchor portion2d which projects into and snugly fits within the said notch 23. Theextent of offset of the terminal wire 52 is preferably sufflcient toassure the-positive interlock of the anchor portion 24 with the notch23, the anchor portion 24 in the particular case shown extendingapproximately to the center of the boss 5. As shown, th mount 8 isanchored in a definite rotative position within the envelope i with thestay member 9 positioned, within the reflector l on the envelope,preferably mid-way between the opposite side edges of the saidrefiector. In this way, the stay member 9 is shieldminal wire i3 issecured to the other end of the said channel member ll by a short lengthof glass rod it which is fused to the said parts and serves to insulatethe terminal Wirel? from the channel member ll.

The filament it: is in the form of a coiled tung- I sten wire which isstretched out so as to extend As shown in Fig. l, the filamentlilextends substantially the entire length of the envelope l and isclamped or other,- wise electrically connected at its ends'to short spurwires it, it welded to the terminal wires 82 and i3, respectively. Thefilament it is supported at intermediate .points along its length bysupport wires ill extending from the channel member ii at spaced pointstherealong, the said support wires being secured to and insulated from.

the channel member by means of small glass beads l8 fused to thesaidparts. v

As shown, the terminal wires or end conductors l2, to extend from theopposite ends of the channel member M at a slight angle relativethereto, and their free'or outer ends are bent to extend most and theloop ed within the reflector i and so does not interfere with thepassage of light out through the clear or light transmitting portion ofthe envelope so as to cast undesirable shadows.

'In making the lamp according to the invention,

the end cap t is first sealed to one end of the glass tube 2 after whichthe lamp mount ii is inserted in the tube with its terminal wire itforel9 on the said terminal wire it then fitted over the boss t on thesaid end transversely of the channel member is and are formed into loopsI?) which encircle the bosses 5, 8 on the respectively adjacent end capsto thereby position the lamp mount 8 within the envelope l with thefilament l6 extending more or less axially of the said envelope. Theloop it on terminal wire it (and also on the other terminal wire l2 ifdesired) is initially formed with a slight pitch or spiral shape, 1. e.,it is formed as a coil of less than one full turn, for the purpose ofmaking the stay member 9 resiliently com-- pressible to a slight extentlongitudinally thereof. During the manufacture of the lamp, the spiralshaped loop or'loops' 89 more or less fiatten out as the stay member 9is compressed between the opposite end caps 3, (l, the loops l9 thusresiliently bearing against the concave inner side of the endcaps and.so making good electrical contact therewith. Where the mount 8 is ofappreciable length, one or more intermediate lateral supports or springbridges 26 may be provided for the purpose of stiffening the mount andpreventing vibration thereof, The said bridge 26 may comprise a U-shapedspring wire disposed transversely of the envelope i with its base weldedto the channel member Hand it free ends yieldingly engaging oppositesides of the glass tube 2.

cap Q. The other or notched end cap 3 is then sealed to the other end ofthe glass tube 2 with the boss 5 on the said cap 3 fitted into the loopis on the terminal wire l2 and the ofiset anchor portion 2d of theterminal wire i2 locked in the notch 23 in the end cap. During thesealing of the notched end cap 3 to the end of the tube 2, the said capis moved or pressed longitudinally inward of the tub to efiect a goodseal therebetween and to compress the composite stay memher 9 betweenthe opposite end caps 3, 41. In this connection; the loop E9 on theoffset terminal wire i2 is preferably formed of flat, rather than of thespiral shape mentioned hereinbefore, and is so spaced from the ofisetanchor portion 26 lengthwise of the envelope as to cause the said anchorportion of the terminal wire i2 to resiliently bear against the .end cap3 rather than the loop in thereof, as shown in Fig. 4; In this way, theuse of the interlocking means 2i according to the invention permits themount 8 to'be placed under a greater amount of longitudinal compressionthan heretofore between the opposite end caps to thus assure betterelectrical contact therewith, without causing a crooked end cap 3, sincethe expansive pressure of the mount is applied by the anchor portion 24to the center of the end 3 where there is no tendency to cause it to Asapplied to lamps of the character described,

. the feature of an, elongated reflector or other light-modifying meanson the glass tube in combination with means for locking the mountagainst rotation and in a definite rotative posi-v tion relative to thereflector orother light-modifying means is disclosed and claimed inco-pending U. S. Application LD1077, P. 0. C-artun, filed of even dateherewith and assigned to the as- 1. An electric lamp comprising atubular glass envelope having metal end caps sealed to and closing itsopposite ends, each of said end caps having a boss projecting inwardlyof the envelope, a mount within said envelope comprising an elongatedfilament extending longitudinally of the envelope and afilament-supporting elongated stay member extending longitudinally ofand compressed between the end caps of the envelope and provided withend conductors electrically connected to said filament, said endconductors each having a loop portion encircling the boss on therespectively adjacent end cap, and means on said stay member engagingone of said end caps to lock the said mount against rotation within theenvelope.

2. An electric lamp comprising a tubular glass envelope having metal endcaps sealed to and closing its opposite ends, each of said end capshaving a boss projecting inwardly of the envelope, a mount within saidenvelope comprising an elongated filament extending longitudinally ofthe envelope and a filament-supporting elongated stay member extendinglongitudinally of and compressed between the end caps of the envelopeand provided with end conductors electrically connected to saidfilament, said end conductors each having a loop portion encircling theboss on the respectively adjacent end cap, and interengaging means onone of said end conductors and the adjacent end cap for locking the saidmount against rotation within the envelope.

3. An electric lamp comprising a tubular glass envelope having metal endcaps sealed to and closing its opposite ends, each of said end capshaving a boss projecting inwardly of the envelope, a mount within saidenvelope comprising an elongated filament extending longitudinally oithe envelope and a filament-supporting elongated stay member extendinglongitudinally of and compressed between the end caps of the envelopeand provided with end conductors electrically connected to saidfilament, said end conductors each having a loop portion encircling theboss on the respectively adjacent end cap, and means comprising ananchor portion on one or said end conductors fitting into a notch in theadjacent end cap to lock the said mount against rotation within theenvelope.

4. An electric lamp comprising a tubular glass envelope having metal endcaps sealed to and closing its opposite ends, each of said end capshaving a boss projecting inwardly of the envelope, a mount within saidenvelope comprising an elongated filament extending longitudinally ofthe envelope and a filament-supporting elongated stay member extendinglongitudinally of and compressed between the end caps of the envelopeand provided with end conductors electrically connected to saidfilament, said end conductors each having a loop portion encircling theboss on the respectively adjacent end cap, and means comprising a notchin the top wall of the boss on one of said end caps and an anchorportion on the adjacent end conductor projecting into and locked withinthe said notch to thereby prevent rotation of the mount within theenvelope.

5. An electric lamp comprising a tubular glass envelope having metal endcaps sealed to and closing its opposite ends, each of said end capshaving a boss projecting inwardly of the envelope, a mount within saidenvelope comprising an elongated filament extending longitudinally ofthe envelope and a filament-supporting elongated stay member extendinglongitudinally of and compressed between the end caps of the envelopeand provided with end trically connected to said filament, said endconductors each having a loop portion encircling the boss on therespectively adjacent end cap, one of said end caps having a notchformed in the top wall of the boss thereon, and the end conductoradjacent the said one end cap having an intermediate portion thereofbent to provide a laterally extending anchor portion projecting into andlocked within the said notch to thereby prevent rotation of the mountwithin the envelope.

WINF'IELD H. WILLIS.

conductors elec-

